Personality factors related to shift work tolerance in two- and three-shift workers

This study aimed to investigate whether different personality variables were associated with shift work tolerance, and whether these potential associations were moderated by various types of shift work. The sample comprised 1505 nurses who worked either two or three rotating shifts. Personality traits were measured in terms of morningness, flexibility, languidity and hardiness. Morningness reflects the tendency to be alert relatively early in the morning and sleepy relatively early in the evening. Flexibility denotes the ability to both work and sleep at odd times of the day, while languidity concerns the tendency to become tired/sleepy when cutting down on sleep. Hardiness relates to resilience to stressful life events. The dependent variables in this study comprised of measures of insomnia, sleepiness, depression and anxiety. Hierarchical regression analyses, which controlled for demographic variables and work load, revealed that Morningness was significantly and negatively related to insomnia. The Morningness by Shift type interaction was overall significant for depressive symptoms. Morningness was near significantly associated with lower levels of depressive symptoms in three-shift workers, but unrelated to depressive symptoms in two-shift workers. Flexibility was associated with higher levels of depressive symptoms. Flexibility by Shift type interaction was significant for insomnia, indicating that flexibility was negatively associated with insomnia for three-shift workers and unrelated with insomnia for two-shift workers. Languidity was associated with higher levels of sleepiness, depressive and anxiety symptoms. Hardiness was associated with lower levels of all four dependent variables.     

What roles do team climate,roster control,and work life conflict play in shiftworkers' fatigue longitudinally?

The study aimed to examine shiftworkers fatigue and the longitudinal relationships that impact on fatigue such as team climate, work life conflict, control of shifts and shift type in shift working nurses. We used a quantitative survey methodology and analysed data with a moderated hierarchical multiple regression. After matching across two time periods 18 months apart, the sample consisted of 166 nurses from one Australian hospital. Of these nurses, 61 worked two rotating day shifts (morning & afternoon/evening) and 105 were rotating shiftworkers who worked three shifts (morning afternoon/evening and nights). The findings suggest that control over shift scheduling can have significant effects on fatigue for both two-shift and three-shift workers. A significant negative relationship between positive team climate and fatigue was moderated by shift type. At both Time 1 and Time 2, work life conflict was the strongest predictor of concurrent fatigue, but over time it was not.     

Influence of shift work in process industry on workers' occupational health,productivity, and family and social life: An ergonomic approach

Shift work is a major feature of modern work practices. It involves working at times considered unconventional for most workers, such as at night. Although the community often benefits from such work practices, shift work can be hazardous for both the workers and the community. There are increased risks for accidents and errors, increased sleepiness and fatigue due to difficulties sleeping, increased health problems, and disruptions to family and social life. More shift workers complained of sleep disturbance, poor sleep quality, tiredness at awakening, and sleepiness in work than did non‐shift workers. More shift workers also complained of gastrointestinal disturbances than did non‐shift workers. The aim of this article is to provide general information on shift work, work schedules, and the effects of work schedules on sleep, fatigue, performance, the health of the human operator, and productivity. © 2010 Wiley Periodicals, Inc.     

How well do truck drivers sleep in cabin sleeper berths?

The aim of this study was to evaluate the sleep obtained by livestock transport truck drivers while resting in truck sleeper berths during long-haul commercial operations. Operations were carried out in the very remote regions of Australia. The sample comprised of 32 drivers who wore wrist activity monitors and reported bed-times for a two-week period. Drivers had a mean (±standard deviation) age of 35.41 (± 9.78) years and had worked as truck drivers for 13.83 (± 9.11) years. On average, they obtained 6.07 (± 1.18) hours of sleep/24-h period. The majority of sleep occurred at night, but drivers occasionally supplemented their main sleep with a daytime nap. Consistent with operational demands, drivers were most likely to sleep in cabin sleeper berths (n = 394, 77%). Only a small proportion of sleeps were sampled at home (n = 63, 12%) or at truck depots (n = 56, 11%). Mixed-model ANOVA revealed that while earlier bed-times at home yielded more sleep, there were only marginal differences in sleep quality across location. No intrinsic safety concerns associated with the use of sleeper berths were identified across consecutive days of long-haul transport operations.     

The effects of frequently rotating shiftwork on sleep and the family life of hospital nurses

The effects of three frequently rotating shifts in an irregular sequence on the daily activities of 239 Japanese female hospital nurses were studied by the time-budget method. The nurses recorded their daily activities for several consecutive days. The questionnaire was returned by 80·8% of the participants, and recordings of 1016 days were analysed. A two-way analysis of variance clarified that the shift combination influenced the daily activities. The most distinct result was that nurses spent significantly more time on free-time activities on the day when they worked the night shift followed by the evening shift than they did on the day when they worked any other shift combination. Nurses offset sleep deprivation either by sleeping during the day before and after working the night shift (82–100%) or by sleeping 2 to 4?h later in the morning after working the evening shift and on days off. There was a strong positive correlation between total sleep time (including day sleep) and the length of the interval between two consecutive shifts (r = 0·95, p < 0·001). This result suggests that more than 16 h between work shifts is required to allow more than 7?h of total sleep time. In an analysis by household status, nurses who had young children (average age, 2·8 years) slept less and spent less time on free-time activities than did other nurses.     

Tolerance of shift work

This study aimed to explore criteria for shift work tolerance and to investigate the relationships between personality traits and states and shift work tolerance. Eighty-nine policemen and police women completed a questionnaire, once during consecutive night shifts and again during rotating shifts, and their responses were used to assess anxiety, emotional control, positive and negative affect, health complaints, sleep quality, difficulties in social and domestic life, and perceptions about shift work. Both the criteria for tolerance and the relationship between tolerance and personality varied according to shift type. Night shift tolerance involved four factors--somatic health, flexibility, sleep and sleep need--while rotating shift tolerance involved three factors--somatic health, flexibility and fatigue. Tolerance of shift work was associated with anxiety, repressive emotional style and mood. During night shifts, anxiety was the most influential personality factor for the somatic health and sleep dimensions of shift tolerance. During rotating shifts, positive and negative moods, rather than trait personality factors, were important predictors of the somatic health and fatigue shift tolerance dimensions. These results suggest a mechanism for more effective matching of workers to suitable shift schedules.     

Worktime control-dependent reductions in fatigue, sleep problems, and depression

We investigated the association between worktime control and fatigue, sleep problems, and depressive symptoms in a sample of daytime and shift workers. A total of 3681 permanent daytime workers and 599 shift workers completed a questionnaire designed to assess the above variables. Worktime control was evaluated in terms of both “control over daily working hours” and “control over days off”. Worktime control × work schedule × gender analysis of covariance, adjusted for age and employment status, showed overall reductions in incomplete recovery, insomnia symptoms, daytime sleepiness, and depressive symptoms with increasing levels of worktime control. However, no associations between control over daily working hours and insomnia symptoms were observed in women. The reductions appeared to be more evident for control over days off. These results remained consistent after adjustments for other potential covariates. The present findings indicate that increased worktime control and enhanced control over days off in particular, may be associated with favorable health outcomes.     

Sleep and circadian rhythms in mining operators: limited evidence of adaptation to night shifts

Cumulative sleep deprivation is often associated with work patterns involving night shift or early morning shifts. Adaptation of the circadian system to the shift pattern is reported to promote improved duration and quality of sleep and a concurrent improvement in performance. The current study followed twenty-nine operators at a live-in mining operation working to a seven-day, seven-night shift pattern who collected saliva samples for melatonin measurement, recorded sleep using activity monitors and diaries, and underwent performance testing (psychomotor vigilance task) for one complete roster cycle. The time of onset of melatonin secretion changed significantly (P=0.022) across the week of both Day and Night shifts (2104 h ± 16 min versus 2130 h ± 16 min, respectively), but the small magnitude of the change indicates a lack of true circadian rhythm adaptation to the lifestyle. Total sleep time was longer following the seventh Day shift (associated with a period of 24 h off prior to the commencement of Night shifts). There were no other changes in total sleep time. Further, there were no improvements in sleep onset latency or sleep efficiency on Day or Night shifts. However, reaction times recorded at the end of the shifts slowed across the seven Day and seven Night shifts indicative of impairments in psychomotor performance (F(6,168)=6.087, P<0.001). The results suggest that previous reports of adaptation to consecutive night shifts cannot necessarily be applied to onshore or Australian environments. Adaptation is dependent on factors such as light exposure, environmental conditions, shift parameters such as wake-up, work start and work end times and individual characteristics.     

Experimental Studies of Shift-Work I: A Comparison of ‘ Rotating ’ and ‘ Stabilized ’ 4-hour Shift Systems

Abstract

Efficiency at ‘ mental ’ tasks was observed when performed according to a time schedule imposed by following one of two different 4-hour shift systems for a period of 12 consecutive days. Twenty-eight subjects were assigned either to a ‘ rotating ’ system, in which each 4-hour period of the 24 hours was worked once every 72 hours in a repeating cycle, or to a ‘ stabilized ’ system, in which the work periods were from 1230 to 1630 and 2400-0400 each day. In the rotating system, alterations in the level of several aspects of performance at different times of day were found to be related quite closely to concurrent fluctuations in body temperature arising from its natural circadian rhythm. A shift in the phase of this rhythm in response to the now sleep/waking cycle imposed by the stabilized system was accompanied by a corresponding change in the relative levels of performance observed in the two work periods. Thus in both systems body temperature was, in effect, a predictor of performance efficiency. Some implications for the organization of shift working are discussed     

Designing better shift systems

The results of some intervention studies on the effects of the change from weekly rotating to quicker rotating shift systems are presented. Consequently, the following recommendations for the design of shift systems according to physiological, psychological and social criteria are discussed: (1) Nightwork should be reduced as much as possible. If this is not possible, quickly rotating shift systems are preferable to slowly rotating ones. Permanent nightwork does not seem to be recommendable for the majority of shiftworkers. (2) Extended workdays (9-12 hours) should only be contemplated when the nature of work and the workload are suitable for extended working hours, and the shift system is designed to minimize the accumulation of fatigue and toxic exposure is limited. (3) An early start for the morning shift should be avoided. Flexible working time arrangements can be achieved in all shift systems. The highest flexibility is possible in the so-called 'time autonomous groups'. (4) Quick changeovers (e.g. from night shift to afternoon shift on the same day) should be avoided. The number of consecutive working days should be limited to five-seven. Every shift system should include some free weekends with at least two consecutive days off. (5) The forward rotation (phase delay, clockwise rotation: morning/evening/night shift) would seem to be most preferred.     

Influence on working hours among shift workers and effects on sleep quality – An intervention study

The aim of the present intervention study was to examine if increased influence on working hours among shift workers led to better sleep quality.391 employees were categorized into groups based on the performed activities: High (self-rostering), moderate (education and/or policy for working hours), and low intensity intervention (meetings and discussions) and reference. Sleep quality was assessed by Karolinska Sleep Questionnaire (KSQ) at baseline and follow-up (12 months). To elucidate the process of the intervention interviews were conducted.Influence on one’s own working hours increased only in the high intensity group (p < 0.001). No effects of interventions on sleep quality were observed. Thus, sleep quality was not improved by increasing work time influence in the present group of Danish elder care workers. This was partly due to program failure (failed intervention), but may also be due to other factors such as few participants working night and few working full time.     

Police officers attitude to different shift systems: association with age, present shift schedule, health and sleep/wake complaints

It is often claimed that shift workers give priority to long series of days off and therefore prefer compressed work schedules at the expense of what is optimal for long-term health. The aim of the present study was to evaluate the attitude to six new shift systems among a randomly selected sample of police officers. The results showed that the most popular shift system was a rapidly, forward, rotating schedule with at least 16 h of rest between shifts, despite that it had fewer days off compared with some of the compressed shift systems. However, the individual differences were large and many individuals (32%) disliked the rapidly rotating shift system. Young age was associated with a positive attitude to the rapidly rotating shift system. The attitude to the shift system was also influenced by the present schedule, and shift systems that were similar to the present work hours received more positive evaluation. Sleep and health complaints showed no association with the attitude to the shift systems. In conclusion, the shift workers attitude to the new schedules was partly in agreement with the ergonomic recommendations of the design of three-shift systems that will facilitate sufficient sleep and minimize negative health consequences.     

Rail signallers' assessments of their satisfaction with different shift work systems

This paper describes rail employee views on shift-work systems obtained from administration of the Rail Ergonomics Questionnaire (REQUEST) to a large sample of rail professionals in Great Britain, achieving a response rate of 83%. Results from signallers, the largest occupational grouping in the survey (n = 3230), are presented. ANOVA has been used to investigate the effects of different aspects of the shift patterns (the length of shift and the speed and direction of rotation of shifts) and the effects of age on the ratings of satisfaction with the shift system. The findings from the analyses indicate preferences for the 12-h shift system over the 7-9-h rotating shift system. There were no main effects of the direction of rotation of shifts, though there were significant interactions between the direction of rotation of shifts, the numbers of consecutive shifts and the age of respondents. There is a need for clear data addressing the impact on workers of key shift-related parameters such as shift length, direction of rotation of shifts, numbers of consecutive shifts and personal factors such as age. This paper presents findings of the effects of these key shift and personal parameters and their interactions on respondents' ratings of satisfaction with the shift system, using data collected with REQUEST in a national survey of rail signallers.     

Main and interactive effects of shiftwork, age and work stress on health in an Italian sample of healthcare workers

Among healthcare workers, shiftwork (mostly if nightwork is also included), ageing and work-related stress may be factors leading to impaired health. Such risk factors may also operate in interaction, resulting in an even increased harm for health. The present study aims at evaluating these relationships in a sample of 1842 hospital workers in Northern Italy. Subjects were mainly women, 33.1% were aged > or = 45 yr, and they were almost evenly distributed between dayworkers and rotating shiftworkers (nights included). Shiftwork was associated with poor sleep, while it was protective against gastrointestinal disorders, poor work ability and job dissatisfaction. Work stress was the risk factor with the highest relevance for poor health. Ageing was associated with lower physical health. Few significant interactions were observed. Shiftwork with nights and high work stress significantly interacted in increasing the risk for poor sleep. The "healthy worker effect" may have played a strong role in study findings.     

The design of shift systems

All shift systems have advantages and drawbacks. There is no single ‘optimum shift system’ which can be used in industry or commerce at all work places. However, there are shift systems which are more favourable, and others which are less favourable, in the context of physiological, psychological, and social recommendations for the design of shift systems. This article discusses the following recommendations:

(1) Nightwork should be reduced as much as possible. If this is not possible, quickly rotating shift systems are preferable to slowly rotating ones. Permanent nightwork does not seem to be advisable for the majority of shiftworkers.

(2) Extended workdays (9-12 h) should only be contemplated, if the nature of work and the workload are suitable; the shift system is designed to minimize the accumulation of fatigue; there are adequate arrangements for cover of absentees; overtime will not be added; toxic exposure is limited; and if it is likely that a complete recovery after work and a high acceptance of the working time arrangement are possible.

(3) An early start for the morning shift should be avoided. In all shiftsystems flexible working time arrangements- are realizable. The highest flexibility is possible in ‘time autonomous groups’.

(4) Quick changeovers (e.g., from night to afternoon shift at the same day or from afternoon to morning shift) must be avoided. The number of consecutive working days should be limited to 5-7 days. Every shift system should include some free weekends with at least two successive full days off.

(5) The forward rotation of shifts (phase delay, clockwise rotation) would seem to be recommendable at least in continuous shift systems.

Besides the design of a shift system, implementation strategy is of particular importance for the acceptance of the shift system.     

Operational assessment of the 5-h on/10-h off watchstanding schedule on a US Navy ship: sleep patterns,mood and psychomotor vigilance performance of crewmembers in the nuclear reactor department

We assessed sleep patterns, psychomotor vigilance performance, work demands and mood of 77 crewmembers of USS NIMITZ (CVN-68) on the rotating 5-h on/10-h off (5/10) watchstanding schedule. Within the 3-day cycle of the 5/10, sleep occurred at distinctly different times each day. On two of these days, sailors typically received only brief, 4-h sleep episodes followed by periods of sustained wakefulness (approximately 22 and 20 h). Crewmembers received approximately seven hours of sleep daily, but reported excessive fatigue and dissatisfaction with their schedule. Crewmembers’ mood worsened significantly over the course of the underway phase. Psychomotor vigilance performance (reaction times, lapses) was significantly degraded compared to performance when working circadian-aligned schedules. Overall, standing watch on the 5/10 schedule, combined with other work duties, resulted in poor sleep hygiene. Crewmembers on the 5/10 experienced periodic bouts of sustained wakefulness and accrued a significant sleep debt due to extended workdays and circadian-misaligned sleep.

Practitioner summary: We assessed crewmembers’ sleep patterns, psychomotor vigilance performance and work demands when working a rotating 5-h on/10-h off (5/10) watchstanding schedule. The 5/10, combined with other work duties, resulted in poor sleep hygiene. Crewmembers experienced periodic bouts of sustained wakefulness and accrued a significant sleep debt due to extended workdays and circadian-misaligned sleep.     

Self-reported health and well-being amongst night security guards: a comparison with the working population

The present study sought to relate the well-being of night workers to that of the working population in general. One hundred and ninety-seven male permanent night security guards were interviewed with regard to the occurrence of various symptoms during the previous 12-month period. The results were compared with the results from similar interviews with a representative national sample of males (n = 1769) in the Swedish workforce. An age standardized morbidity ratio was computed with control for various background variables. The results showed that the security guards had a 2-3 times higher occurrence of sleep disturbances and fatigue than the national sample. Among the variables not differing from the national sample were gastrointestinal problems, headache, nervous problems, depression, nausea, diarrhoea, and haemorrhoids. It was concluded that sleep/wake disturbances are considerably more usual in permanent night security guards than in the working population as a whole.     

新型电火花表面强化机的研制

现有电火花表面强化的设备大多是手工操作的小功率设备,效率低,强化层薄且均匀性差.本文针对现有设备表面强化质量较差的问题,详细介绍了一种新型电火花表面强化机的工作原理,各单元电路的组成及整个系统工作过程.新型电火花表面强化机采用无触点开关作为开关元件来控制火花放电,并采用旋转电极方式和氩气保护系统,工作稳定可靠,可达到较...     

A field study of sleep and fatigue in a regular rotating 12-h shift system

The aim of this study was to examine a regular rotating 12-h shift system (2D2N4Off) at an Australian Smelter. Sleep behavior, subjective fatigue and neurobehavioral performance were investigated over a 14-day period for 20 employees. Activity monitors, sleep/wake diaries, and 5-min psychomotor vigilance tasks were used. Sleep data showed differences between day and night shifts. While sleep prior to night1 was increased relative to day shifts, a reduced sleep length carried into the period leading to night2. Total wakefulness at the end of shift, and subjective fatigue were increased for night shifts, particularly night1. Decrements in performance data supported these findings. Both prior wakefulness and prior sleep are important in a 12-h shift system. Employees may “sleep in” after day shifts, rather than taking extra sleep prior to night work. Thus, sleep between day and night shifts is based on recovery rather than preparation.     

Systematic selection of shift plans for continuous production with the aid of work-physiological criteria

Taking into account the numerous theoretically possible shift systems, we chose sensible shift systems with the aid of objective work-physiological criteria, eg, the duration of the daily working time, the positioning and duration of sleep and recreation time. With an agreed 40 h week shift, systems with a weekly working time of 42 h are more advantageous. If the shifts are equally attended over 24 h the following shift systems are recommended: when you have 8 h shifts the relation between the number of working days and the number of free days should be "3 n/n", whereby n must be larger than 1, within one shift rota. In the exceptional case of a 12 h shift the corresponding relation should be "2 n/n". Further unsuitable and recommended shift plan examples are demonstrated for these shift systems.